Self-priming liquid-pumping system

ABSTRACT

A self-priming liquid-pumping system has a main pump which draws liquid from a tank at a lower level and includes a priming reservoir above the main pump and which has a capacity larger than that of the piping between the main pump and the tank. A secondary pump may be provided to remove vapor from the reservoir. The system is primarily intended for use in the fuel system of a helicopter, in which a main centrifugal pump driven from the engine is preferable.

United States Patent 1 3,584,979

[ 72] Inventor Michael Peter Jarrett [56] Reference Cited 21 A l N gig'gf UNITED STATES PATENTS f Aprza 1969 2,823,613 2/1958 Leduc 103/113 [45] Patented June 15, 1971 Primary Examiner-Henry F. Raduazo [73] Assignee Joseph Lucas Industries Limited Attorney Holman & Stern Birmingham, England ABSTRACT: A self-priming liquid-pumping system has a main pump which draws liquid from a tank at a lower level and [54] SELF'PRIMING LIQUID'PUMPING SYSTEM includes a priming reservoir above the main pump and which 2 Clams 1 Drawing has a capacity larger than that of the piping between the main [52] U.S.Cl 417/89 pump and the tank. A secondary pump may be provided to [51] Int. Cl F 04d 9/00 remove vapor from the reservoir. The system is primarily in- [50] Field of Search 103/113 J, tended for use in the fuel system of a helicopter, in which a 1 13 R, 5; 415/80, 88, 89, 76 main centrifugal pump driven from the engine is preferable.

PATENTEDJUHISIQTI 35841979 flaw fgalNvENTOE BY ATTaENEYS SELF-PRIMING LIQUID-PUMPING SYSTEM This invention relates to a self-priming liquid-pumping system.

A self-priming liquid-pumping system in accordance with the invention comprises a main pump arranged to draw liquid through piping from a tank at a lower level than said main pump, characterized by a priming reservoir at a level higher than the main pump and of a volume sufficiently greater than the volume of said piping to enable the removal of liquid from the priming reservoir to draw liquid into the priming reservoir.

An example of the invention is illustrated in the accompanying drawing which is a diagrammatic representation of the pumping system.

The system includes a centrifugal pump 10, the inlet of which is connected to a priming reservoir 11. The reservoir 11 is connected via piping 12 to a tank 13 at a lower level than thepump 10. The volume of the priming reservoir 11 is chosen so as to be greater than the volume of the piping 12 by an allowance determined in accordance with the vapor pressure in the most adverse conditions under which the system has to operate plus an allowance dependent on the volume change in the piping in the most adverse conditions.

For removing vapor from the reservoir 11 there is an injector pump 14, the nozzle 15 of which draws liquid from the high-pressure side of the pump 10. The inlet 16 of pump 14 is connected to the uppermost part of the reservoir 11 and its outlet is connected by piping 17 to the tank 13.

The system is intended to be employed in the fuel system of a helicopter in which a main tank is situated in the lowermost part of the fuselage with gravity feeds from various suppleis used with a shutoff cock 18 on the high pressure side of they pump 10, so that fuel in the pipework between'the pump 10 and the shutoff cook 18 can run back into the reservoir 11 on shutdown.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

l.. A self-priming liquid pumping system comprising a main pump arranged to draw liquid through piping from a tank at a lower level than said main pump, a priming reservoir at a level higher than the main pump and of a volume sufficiently greater than the volume of the said piping to enable removal ofliquid by the main pump from the priming reservoir to draw liquid into the priming reservoir and an injector pump supplied, in use, with liquid from the main pump, an inlet of the injector pump being connected to-the priming reservoir adjacent an upper end thereof and the outlet of the injector pump being connected to the said tank.

2. A system as claimed in claim 1 in which the volume of the priming reservoir is greater than the volume of the said piping by an allowance depending on the vapor pressure plus an allowance depending on the volume change in the piping, both the said allowances being determined in accordance with the most adverse conditions under which the system has to operate. 

1. A self-priming liquid pumping system comprising a main pump arranged to draw liquid through piping from a tank at a lower level than said main pump, a priming reservoir at a level higher than the main pump and of a volume sufficiently greater than the volume of the said piping to enable removal of liquid by the main pump from the priming reservoir to draw liquid into the priming reservoir and an injector pump supplied, in use, with liquid from the main pump, an inlet of the injector pump being connected to the priming reservoir adjacent an upper end thereof and the outlet of the injector pump being connected to the said tank.
 2. A system as claimed in claim 1 in which the volume of the priming reservoir is greater than the volume of the said piping by an allowance depending on the vapor pressure plus an allowance depeNding on the volume change in the piping, both the said allowances being determined in accordance with the most adverse conditions under which the system has to operate. 